The optical mouse has been overwhelmingly popular for controlling functions of computers and other electronic devices. However, the conventional optical mouse is too big and unsuitable for use in many portable electronic devices such as personal digital assistants, telephones, etc. Accordingly, other types of conventional input devices, such as TouchPad™ devices and puck-based input devices, have been developed and embedded into portable electronic devices, such as laptop computers, phones, etc. These input devices have become more important as portable electronic devices continue to incorporate more functionality, such as electronic mail, wireless computing, photography, etc.
Conventional puck-based input devices are attractive for handheld electronic devices because of their low profile. In some conventional puck-based input devices, a resilient mechanism, such as a spring, is deployed in association with the puck to maintain a desired position of the puck. The resilient mechanism is arranged to bias the puck to return to a center position after the puck has been moved to an off-center position, in which the user captures a user input. Unfortunately, the resilient mechanisms in conventional puck-based input devices either typically provide inaccurate and sloppy re-centering of the puck, or do not have a small enough form factor for many portable electronic applications.
In rate control devices such as the IBM TrackPoint™ the position of the puck maps to the velocity of the cursor. For rate control devices, accurate recentering is important because if the puck is not returned precisely to center, the cursor may drift when the user is not touching it. To work around this problem, these conventional input devices typically employ a sufficiently large central “dead zone,” or use a very stiff restoring spring, both of which are detrimental to a good user experience. The Neuropointer™ by NEC is an example of a conventional portable puck-based navigation device which uses a rubber membrane to re-center the puck. Because the membrane is essentially a linear spring, the recentering accuracy is relatively poor.
Other conventional input devices attempt to address the accuracy of re-centering a puck with re-centering mechanisms having alternative force restoring force profiles. Unfortunately, these conventional input devices are too thick to fit in many portable electronic devices.
Users continue to demand more precision and accuracy in user input devices of portable electronic devices, while designers face continual pressure toward increasing miniaturization and increased functionality. With these challenges, conventional input devices fall short of market expectations by exhibiting inaccurate puck centering and positioning.